Grinding machine



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` July 24,A 1923.4

' ,W. C..OSTERHOLM GRINDING MACHINE Filed June l0 Smmmw A @my hw, mh,

July 24, 1923.

, 1,462,653 w. c. psrERHoLM v GRINDINGA MACHINE 6 Sheets-Sheet 6 Filed June l0 1921 ION .I-III l MEM Ill/IIln ETED erica;

WILLIAM C. OSTERHOLM, 0F CHICAGO, ILLINOIS, ASSIGNOR TO OSTERI-IOLM AUTU- MATIC MACHINE GO., OF CHICAGO, IL

' GRINDING Appuation filed :rune 1o,

Be it known that I, WILLIAM C'. OSTER- HoLM, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful `Improvements in Grinding Machines, of which the following is a specification.

The present invention relates to grinding machines.

More particularly, the `present invention relates to machines for surface grinding work where said work is to be done in quantity production.

An object of the present invention is to provide a grinding machine in which the work may be expeditiously set up and in which'the grindingoperation may be per formed with a minimum of attentionby an operator.

A further object is to provide grinding machinery in which wear of the grinding wheel may be readily compensated for whereby such wear will not cause material delays in operation.

A further object is to provide grinding machinery in which a widerange of ad@ justability is readily accomplished.

A further object is to provide grinding machinery in which shocks will be cushioned between work and grinding wheel.

A further object is to provide grinding machinery. in which the relative speed Vof translation between the grinding wheel and the work may be readily changed.

A further object is to provide machinery in which a work table is convenient-ly located for the mounting of work thereon and which will'` be moved automatically into proper position for the grinding operation.

A further object is to provide grinding machinery which, after accomplishing a predetermined amount of grinding, will automatically shut off and vwhich may be readily stopped at any time by the operator.

A further object is to provide grinding machinery in which the number of operations required to be performed by an operator is reduced to a minimum.

Further objects will appear as the description proceeds.

Referring to the drawings, Figure l is a side elevation illustrating one embodiment ofthe present invention.

LINOIS, A CORPORATION 0F ILLINOIS.

MACHINE.

1921. Serial No. 476,409.

Figure 2, is a view in end elevation of the structure illustrated in Figure .1.

Figure 3 is a top plan view`of`the structure shown in Figure l.

Figure 4 is a sectional view takenalong the `line 4-4 of Figure l.

Figure 5 is a view nend elevation ofthe right hand end ofthe machine asshownv-in Figure l.

Figure 6, is a sectional viewtaken'along the line 6 6 of Figure 3.

Figure 7 is aV sectional viewl takenalong the line 7-7 of Figure 5.

Figure 8 is a sectional View` showing means for accomplishing Vadjustment ofthe work table. The section` shown in 4Figure S is taken along the line 8;8 of `Figure 5.'

Figure 9 is a sectional view taken/along thc line 9-9 of Figure 3.l

Figure l0 isa sectional view takenv along vthe line lO-lO yof'Figurey 3.

Briefly stated,v the present invention involves a tilting worktable which may be tilted to a convenient angle for mounting the work thereon. The inventionlcontem'- plates automatic means for moving said table into proper operating positi'onwvliere'- by` a grinding wheel 'may operate on' the work on said table. Adjusting meansare provided whereby the operating position 'of said table may be accurately adjusted. The grinding wheel referred to hasthe function `of grinding a plane surface andwill 'of course be subject to wear. Means are provided for adjusting the grinding wheel relative to its holding means and'meansare also provided for moving said grinding wheel relative to the propelling mechanism therefor, whereby an operator' may'manually move the grinding wheel "up to the work independently of the automatic feeding mechanism therefor. Means are provided whereby a workman, byv performing" a simple manual operation, will'set forces'in operation which will automatically move the tilting table into operating-position and will produce a feeding motionwherebythe grinding operation will be accomplished. The work will be moved automatically with a reciprocatory movement across the fface of the grinding wheel while the grinding wheel is moved with a feeding motion toward said work.

When a predetermined grinding operation has been accomplished, the feeding will be stopped automatically and the table will be tilted into position for the workman to conveniently remove the finished work and mount a 'new piece of work. Meansare also provided whereby the workmen may stop the feeding operation at any time that he sees fit. Change speed means. are provided whereby the relation may be changed between the reciprocatory motion of the work and the feeding motion of the grind- .ing wheel lnormal to the face of the work.

Other salient features ofthe invention will appear from the detailed description which follows:

The illustrated embodiment of the invention comprises a base 1, which may be a casting, which base provides a bearing surface for the grinding wheel carriage 2;. The carriage. 2 is provided with a pair of bearing members 3-3 which carry a shaft iff Saidv shaft 4 isdriven by a pulley 5 and operates a grinding wheel 6. Said carriage is adapted to have a longitudlnal movement and is operated bv the following mechanism,

1 Mounted uponthe base 1 is slide 7l which is adapted to have a longitudinal movement relative to the base 1, which movement results in feeding the grinding wheel 6 against the work to be operated upon, and will be referred to in detail hereinafter. The slide A7 has a nut 8 mounted therein which carries a screw threaded shaft 9, which shaft 9 isffast to the grinding wheel carriage 2. Suitably mounted upon the carriage 2 are a pair of uprights 10, and 11 which provide the bearings for a longitudinally extending shaft 12. Said shaft 12 is provided with a hand-wheel 13 on one end and with a sprocket wheel 14 on the other end. The shaft 9` is provided with a sprocket wheel 15 andv may be rotated from the sprocket "wheel 14 by means of the sprocket chain i 19 and 20.

16. It will be clear that the. hand wheel 13 maytransmit motion to the shaft 12,

vsprocket wheel-.14, chain 16 and sprocket wheel 15 and so to the screw threaded shaft 9. f The screw threaded shaft 9 in turning in the nut 8, w-ill produce a longitudinal movement of the grinding wheel carriage 2. By this mechanism, the grinding wheel 6 fmay be quickly movedin a longitudinal disaid nut may be moved .to the desired positionlongitudinally of the axis of the shaft 4. The wall 19 is inclined toward the shaft on its inner side so that the space enclosed thereby is of less diameter nearthe bottom of cup 18. Fittingwithin the conical surface provided by the wall 19, is the ring V23 which may be a split ring. Said ring has a conical contouren its exterior surface to fit the surface of the wall 19 and has a cylindrical shape on its interior surface to fit the grinding wheel 6. Bolts 25 serve to draw the ring 23 within the cup 18 to hold the grinding wheel 6 in position. By adjusting the. nut 21, the position of the grinding wheel 6 longitudinally of the shaft 4L may be adjusted.

When the operator has mounted the work iii-position in the manner which will be described hereinafter, he will start operations by operating the rod 26, which will setin motion the mechanism which will have the eect of moving'the work table up into operative position, maintaining the work table in said position'during the grindingoperation, also producing a reciprocatory .movement of the work across the face of the grinding wheel 6 and operating to move said grinding wheel in a longitudinal direction. At 'thecompletion of the cycleinaugurated by operation of rod 2G the work table will. be automatically withdrawn from operative position and the longitudinal or feeding movement of the grinding wheel and the reciprocatory4 movement of the work table will be stopped. The mechanism for producing these results wil now be described. i f

Suitablyv mounted upon the base 1 are a pair of housings 27v andr28. Housing 27 provides bearings for a shaft 29, whichhas .mounted at one end thereof, (Figure 3) the loose pulley 30 and the tight pulley 31 which are adapted to carry the belt 32. A belt shifter 33 is provided for selectively moving said belt 32 from vthe loosepulley to the tight pulley or back again.l i Said belt shifter 33 may be pivoted at any convenient place on the base 1 of the machine and may be operated by the rod 311 which is pivoted to the belt lshifter 33 at the point 35 and is provided with a collar 36 midway of its length. Fast with the base 1 is the spring socket 37 for carrying the spring 38. rlhe spring 38 operates between the spring socket 37 and the collar 36 to urge the belt shiftenin a clockwise direction, whereby to move the belt 32 to the'loose pulley. The rod 26 is connected to the rod34t ofthe belt shifter by means lof the. bellcrank lever having two armsl 39 and lO. TheV belt shifter 33 may beheld againstv the tension of the spring 33 by certain mechanism which may be referred to as knock off mechanism. The belt shifter 33 is provided witha catch member 32 adapted to engage with a catch member 33 carried by the lever 34 which is pivoted at the point 35.

rlhe shaft 29 is provided intermediate of its length with a worm 41, meshing with a worm wheel 42, said worm wheel 42 being keyed to a hollow shaft 43. Said hollow shaft 43 is provided with a pair of internal eccentric bearings 44-44, (Figure 4). These bearings 44-44 which carry the shaft 45, are offset from the center line of the hollow shaft 43. The shaft 45 has at its left hand end a wedge shaped head 46 fitting within a similarly placed pocket 47 in the bearing 44. Said wedge shaped head 46 carries a roller 48, which is adapted to give vertical reciprocatory movement to the rack 49, which is adapted to slide in a suitable bearing 49 fast to the base l. The rack 49 operates a segment 50 which drives a hollow shaft 5l with an oscillating movement, which will be further referred to hereinafter. It may be stated here, that the hollow shaft 5l operates the work table and gives the work a -reciprocatory movement across the face of the grinding wheel 6. IThe throw of the segment 50 may be controlled by the simple expedient of changing the position of the roller` 48 relative to the center line of the hollow shaft 43. Foi the purpose of adjusting the position of the roller 48, the shaft 45 is provided with a squared end 45. A nut 46 is provided for holding the shaft-t5 in adjusted position within the bearings 44--44 of the hollow shaft-43.

The hollow shaft 5l is provided at its right hand end, as shown in Figure l, with a work table support 52. Said work table support has pivotally mounted thereon the work table 53, said pivotal mounting being accomplished by means of the shaft 54. As mentioned hereinabove, oscillating movement of the hollow shaft 5l will result in the reciprocatoi'y movement of the table 53 across the face of the grinding wheel 6. Figure l shows the table 53 in tilted position, whereby the workman may conveniently mount the work to be operated upon. Said table 53 is automatically moved into horizontal position and the longitudinal movement' of the grinding wheel 6 is produced by mechanism which will now be described. A piece of work to be operated upon is indicated in Figure 5 by the numeral 53', said work being held in place by clamps 54.

The shaft 29 which is located within the housing 27 is connected to the shaft 55, located within the housing 28 by means of change speed gearing 56. The relative speeds of shafts 29 and 55 may be readily `changed by simple changes in these gears,

thereby changing the `time duration of the operating cycle. The shaft 55 is Aprovided with a worm 57 which drives a worm wheel 58. The worm wheel 58 drives ya cam housing 59 which carries a pair of cam plates 60 and 6l. The two cam plates 60 and 6l provide a cam groove 62, shown in Figure 1. Withintlie cam groove 62 is a roller 63 which is mounted on the arm 64. The arm 64 drives the shaft 65 through a cushioning connection 66 which will be described hereinafter. The shaft is given an oscillatory movement by the action of the roller 63 within the cam groove 62. This oscillatory movement of the shaft 65 produces the result of moving the work table 53 into operative position and of giving a longitudinal 4movement to the grinding wheel 6, by mechanism which will now be described.

Referring first to the mechanism for moving the table 53, it may be stated that the shaft 65 has depending therefrom a i'elatively long arm 67 adapted to give a reciproeating movement to the rod 68. The rod 68 is connected to the lever 69 which is pivoted intermediate of its length on the shaft 70. The pivotal connection of the lever 69 provides certain features of adjustability which will be described in detail hereinafter. f

Referring now particularly to Figures l and 7, it will be noted that the table 53 is provided on its under side with a cani shaped track 7l.. The lever 69 is provided with a pair of bearings 72*72, adapted to carrythe pin 73, which pin 73 rides upon the cam shaped track 7l. When the` lever 69 is operated in a clockwise direction. the table 53 will be moved into a horizontal position which is the operative position therefor. Vhen the lever 69 is moved in a counterclockwise direction, the table 53 will be moved to its tilted position, which is the convenient position for a workman to mount the work to be operated upon. The pin 73 may be flattened on one side and may be held in adjusted position within the bearings 72-72 by means of the stud 74. The track 7l should preferably have a curve substantially concentric with the axis of rotation of lever 69, during the major portion of the movement of said lever 69, whereby said table 53 will be moved only at the beginning and end of the cycle of movement of said lever 69. The work table support 52 may be provided with a pair of outstanding arms 7 5--75 for providing abutments 76--76 The work table 53 may be provided with a pair of set screws 77-'77 engaging with said abutments 7 6--7 6 when the work table is in `correct horizontal. position.

Anoted that the shaft 65 carries a single tooth 78, which engages with the slide 7. Said slide 7 is connected to the grinding wheel carriage 2 by means of the nut 8 and the screw threaded shaft 9. Oscillating movement of the shaft 65 will therefore result in a reciprocating axial movement of the grinding `wheel 6. A

Referring to the feature of adjustability ofthe lever 69 for operating the table 53, attention is directed to a disclosure in Figuros l, 5 and 8. Referring to Figure 8, it will be noted that the lever 69 is provided with a cylindrical portion 79. The table support 52 provides a bearing for a shaft 70 having a squared end 81. Between the shaft 70 and the cylindrical portion 79 is a. cam

shaped collar 82, which collar 82 is secured to the shaft 70 by means of the pin 83. Pin 83 may be inserted through holesin-the sides of the cylindrical portion 79, which holes ,may be closed by plugs 84-84. ly turningl the squared end 8l of the shaft 80, vertical adjustment of the lever 69 may be had which will result in adjusting the operative position of the work table 53.

As referred to above, the arm 64 is connected to the shaft 65 through a cushioning member 66. This cushioning member is shown in detail in Figure l0. T he cushioning member 66 comprises a split ring portion 85 which may be held in tight engagement with the shaft 65 by means of a bolt 86. The cushioning member 66 is provided with a socket portion 87, which socket portion is adapted to receive a lug 88 which is fast to but offset from the arm 64, which arm 64 may be journalcd on the shaft 65. A spring 89 operates between said lug 88 and `a plug 90 in the `socket portion 87. rllhis spring 89 compensates for shocks which may be encountered due to rough spots on the work to be operated upon, thus allowing a free retrieve of the grinding wheel. A rigid connection between the arm 64 and shaft 65 may be had by turning up the stud 91 which is located within the plug 90.

The mechanism for stopping the motion of the table 53 and the feeding motion of the grinding wheel 6 will now be described.

As hereinabove stated, the belt 32 will be in engagement with the tight pulley 31 (see Figure 3), so long as the catch 32v is engaged with the catch 33. The arm 34 which carries the catch 33 is provided with an offset arm 92 adapted to be operated by a longitudinally movable rod 93. A spring 94 is provided for urging the arm 34 in a clockwise direction. The rod 93 is connected with a bell crank lever pivoted on the shaft 95. Said bell cranklever is indicated by the numeral 96 and has an arm 97 provided with an adjustable pin 98, contacting with the upper side of the arm, 64. Said adjustable pin 98 will be held in engagement with the upper side of said arm 64 by virtue of the spring 94, and when said arm 64, operated by the roller 63 in the cam slot 62,

rises to a predetermined point, the rod 93 will be drawn in a right hand direction as viewed in Figure 3, moving arm y34 in a counterclockwlse direction, releasing catch 33 from the catch 32 and allowing the spring 38 tc move the belt shifter 33 in a clockwise direction to move the belt 32 yon to the loose pulley, thereby stopping the movement of table 53 andI the feeding motion of the grinding wheel 6. The shaft 95 has secured thereto the vertically extending lever 99 (Figure l), which is loperable by the rod 100. It will be clear, that an operator may stopv the motion of the table 53 and the feeding motion of the grinding wheel 6 by simply pushing in a left hand direction against the rod 100.`

A mode of operation of the above described embodiment of the present invention will be clear from the preceding description. lt may be stated briefly that during the time that a workman is operating the machine, the pulley 5 may be continuously operated to rotate the grinding wheel 6. While the workman is mounting the work on the table 53, said table will occupy the tilted position shown in Figure 1. At this time the table 53 will be stationary and there will be no feeding motion in the grinding wheel 6. After the Workman has secured the work on the table 53, he will pull in a right hand direction on the rod 26, which will operate' through the bell crank lever 39-40 and rod 34 to shift the belt 32 from the loose pulley 30 to the tight pulley 3l, thereby setting 1n motion the shaft `29. Motion will be communicated through the change gearing 56 to shaft 55 which, through worm 57 and worm wheel 58 will drive the cam housing 59. Rotation of the cam housing 59 will opera-te the arm 64 about the shaft 65 as a center, `moving said shaft in a clockwise direction as viewed in Figure l. The relatively long arm 67, fast to the shaft 65 will produce a considerable longitudinal movement in the rod 68, which, acting through the lever 69 will move 4the table 53 into a horizontal position.

At the same time that the tilting movement of the table 53 is being accomplished, the shaft 29, operating throughworm 4l and worm wheel 42, will cause the oscillatory movement of the table 53 across the face of the grinding wheel 6. The power for producing this oscillatory movement ,of the table 53 is communicated from the Worm wheel 42 to the hollow shaft 43, offset shaft 45, roller 48, rack 49, segment 50, hollow shaft 5l to support 52 for the table 5.3.

A feeding motion will also be communicated to the grinding wheel 6 by reason of the tooth 78 on the shaft 65, which tooth engages with the slide 7. As the shaft 65 is rocked in a clockwise direction, as viewed in Figure l, the tooth 78 will move the slide 'ana with it ai@ grinding when carriage 2,

` tion has been accomplished. The automatic stopping of the oscillatory movement of the table 53 and the feeding motion of the grinding Wheel 6 will be accomplished When the grinding Wheel 6 has been moved to the limit of its travel in a left hand direction Which is in a direction away from the Work. It Will be clear, that the cycle ofthe feeding movement of the grinding Wheel 6 may be varied by varying the design of the cam groove 62. The Workman may, at any time readily adjust the longitudinal position of the grinding Wheel 6 by turning the hand Wheel 13. Movement of the hand Wheel 13 will vary the relative positions of the grinding Wheel carriage 2 and slide 7 by virtue of the sprocket chain 16, screw threaded shaft 9 and nut 8. The workman, by simply turning the hand Wheel `13 may therefore readily compensate for Wear of the grinding Wheel 6 and for inequalities in the castings to be operated upon. In the event that high spots or particularly hard spots are encountered in the work, cushioning member 66 Will prevent sudden violent shocks. By reason of the arrangement for holding the grinding wheel 6 Within the cup shaped member 19, the grinding wheel may be used until it is practically all used up and will always be firmly held.

Oilers 101 and 102 may be provided for lubricating the Worm Wheels 42 and 58 with their cooperating worms. Water nozzles 103 may be provided for directing the streams of Water on the grinding surface and a catch basin 104 may be provided for catching the Water. v

It will be clear, that by changing the ratio of the gearing 56 between shafts 29 and 55, the speed of oscillation of the table 53 relative to the feeding motion of the grinding Wheel 6, may be readily'varied.

One embodiment of the present invention has been described in detail. Many modifications Will occur to those skilled in the art. It is intended in this patent `to cover all such modifications that Will fall Within the scope of the invention as defined by the appended claims:

What I claim as nen7 and desire to secure by Letters Patent in the United States, is:

1. In a grinding machine, a carriage carrying a grinding wheel, means for propelling said carriage, means for changing the position of said carriage relative to said.

propelling means, means for communicating a feeding motion to said propelling means to move said carriage, a Work table and means for moving said work table with a reciprocatory motion in a plane normal to the line of movement of said carriage.

2. In a grinding machine, a grinding Wheel, having a face normal to its axis, means for feeding said Wheel in the direction of its axis, a Work table, said Work table being movable toward and Way from said Wheel in a direction normal to the face of said Wheel, said table being movable in a direction across the face of said Wheel and means, operating in synchronism, for operating said feeding means and for producing in the table the tivo movement referred to.

3. In a grinding machine, a grinding wheel having a plane face, a member for controlling the feeding of said grinding Wheel in the direction of its axis, a driving shaft for said member, a Work table, adjustable means controlled by said shaft for producing a reciprocating movement of said table across the face of said grinding Wheel and means responsive to rotation of said shaft for moving said table in a direction toward or away from the plane ofthe face of said grinding Wheel.

4. In a grinding machine, a grinding wheel carriage, a grinding Wheel carried thereby, said Wheel having a plane grinding face, a propelling member for moving said carriage with a feeding motion, means for adjusting the' position of said carriage relative to said propelling member, means for driving said propelling member, a work table. means responsive to said driving member for moving said Work table in a direction toward or away from the plane of the face of'said grinding Wheel and means opera-ting synchronously with said driving member for moving said Work table across the face of said grinding Wheel.

5. In a grinding machine, a grinding Wheel, a Work table, a member for quickly setting said Wheel in position to start grinding, means for communicating a feeding motion to said Wheel, means for moving said .vork table in a direction toward or away from the immediate locality of grinding operations, means for moving said table with a reciprocatory movement across the face of said grinding wheel, common mechanism for driving said means, and stopping mechanism responsive to one of said means for rendering inoperative said driving mechanism.

6. In a grinding machine, a grinding Wheel, a Work table, a member for quickly setting said Wheel in position to start grinding, means for communicating a feeding Inotion to said Wheel` means for moving said Work table in a direction toward or away from the immediate locality of grinding operations, means for moving said table with a reciprocatory 'movement across the face of said grinding wheel, common mechanism for driving said means, and stopping mechanism responsive to one of said means for controlling said driving mechanism, said Stopping mechanism including spring means for biasing said driving mechanism to an inoperative condition and knock-off mecha-I nism for maintaining said driving mechanism in operative condition.

7. In a grinding' machine, in combination, a grinding wheel having a plane grinding face, a worky table and driving means for feeding said grinding wheel, for moving said table across the face of said grinding wheel and for moving said table toward or away from the plane of the face of said grinding wheel.y

8, In a grinding machine, in combination, a grinding wheel having a plane grinding face, a work table and driving means for feeding said grinding wheel, for moving said table across the face of said grinding wheel and for `moving said table toward or away from the plane of the face. of said grinding Wheel, said driving means includ ing a shaft and means for translating the rotary motion of said shaft to a reciprocatory motion of said table across said grinding wheel.

9. In a grinding machine, in combination, a grinding wheel having a plane grinding face, a wor table and driving means for feeding said grinding wheel, for moving said table across the face of said grinding wheel and for moving said table toward or away from the plane of the face of said grinding wheel, said driving means including a shaft and means for translating the rotary motion of said shaft to a reciprocatory motion of said table across said grinding wheel, said driving means also including means for communicating a feeding motion to said grinding wheel.

10. In a grinding machine, in combination, a grinding wheel having a plane grinding face, a work table and driving means for feeding said grinding wheel, for moving said table across the face of said grinding wheel and for moving said table toward or away from the plane of the face of said grinding wheel, said driving means including a shaft and means for translating the rotary motion of said shaft to a reciprocatory motion of said table across said grinding wheel, said driving means also including means for communicating a feeding motion to said grinding wheel, said driving means also including means operating synchronously with said feeding means for moving said table in a direction toward or away from the plane of the face of said grinding wheel, said table moving means including wheel having a plane grinding face, a work table, and synchronously operating means for communicating a feeding motion to said grinding wheel and for moving said table toward or away from the plane of the face of said grinding wheel.

12. In a grinding machine, a grinding wheel having a plane grinding face, a work table, and synchronously operating means for communicating a feeding motion to said grinding wheel and for moving said table toward or away from the p-lane of the face of said grinding wheel, the operating means for said table including cam means for quickly moving said table to operative position and holding said position during the grinding operation.

13. In a Igrinding machine, in combination, a grinding wheel and a work table for swinging work across the face of said grinding wheel, said work table being provided with operating means comprising a hollow driving shaft, a shaft eccentrically mounted in said hollow shaft, said eccentrically mounted shaft having a crank and being adjustable to vary the position of said crank relative to the center line of said hollow shaft and connections between said crank and said work table.

14. A grinding machine, comprising a grinding wheel, propelling means for communicating a feeding motion to said grinding wheel, drive means biased to an inoperative condition, knock-off mechanism for maintaining said drive means in operative condition, manual means for setting said knock-od means to establish an operative driving connection, said drive means including means for producing a predetermined cycle of travel of said propelling means, means automatically operated by said drive means for automatically tripping said knock-ofi' means when a predetermined point in said cycle has been reached and manual means for tripping said knock-off means.

15. In a grinding machine, a grinding wheel, a work table, said work table being tiltable toward and away from said grinding wheel, whereby pieces of work to be operated upon may be conveniently mounted on saidA table, a member for tilting said table, said table being provided with a cam shaped track, said member being provided with a bearing portion engaging said track, said track being formed to cause a rapid movement of said table during a portion only of the travel of said table tilting member.

16. In a grinding machine, a grinding wheel, a work table, said work table being tiltable toward and away from said grinding wheel7 whereby pieces of work to be operated upon may be conveniently mounted on said table, a member cooperating with said table for tilting same with a rapid movement during a portion only of the movement of said member. l 17. In a grinding machine,` a tiltable table, a lever for tilting said table, said lever having an adjustable eccentric connection with its fulcrum whereby the tilting effect may be adjusted.

18. In a grinding machine, a tiltable table, a lever for tilting said table, said lever having an adjustable eccentric connection with its fulcrum whereby the tilting eect may be adjusted, said table being provided with adjustable stop means whereby saidtable may be conveniently located in a predetermined position While the eccentricityof said fulh Crum connection is being adjusted.

19. In a grinding machine, a grinding wheel having a plane grinding face, a work table having a reciprocatory mot-ion across the face of said Wheel, means for imparting a feeding motion to said wheel and means operating synchronously with said first mentioned means for communicating reciprocatory movement to said table, said means including transmitting mechanism of which the speed ratio is readily changeable in order to change the number of reciprocations of said table relative to the feeding motion of said wheel.

Signed at Chicago, Illinois, this 7th day of J une, 1921.

WILLIAM C. OSTERHOLM. 

